1. Field of the Invention
The present invention relates to a method for encoding messages with space-time trellis codes(STTC) and transmitting the encoded messages in communication system wherein at least two transmit antennas and at least one receive antenna are provided. The method comprising steps of: generating a codeword by encoding message using STTC; generating a modified codeword by multiplying the codeword by unitary matrix V; and multiplying the modified codeword by weighting matrix W, and then transmitting it through transmit antennas. The weighting matrix W is determined depending on channel information which is fed back to the transmit antenna from the receive antenna. The unitary matrix V is the value that minimizes the union bound of frame error rate, and is chosen by computer search.
2. Description of the Prior Art
Since the introduction of the bandwidth and power efficient methods that realize the benefits of multiple transmit antennas, there has been considerable interest in the space-time codes(STCs). Most work on STCs assumes that the channel information at the transmitter is not available. However, in some communication systems, it is reasonable to assume that channel information at the transmitter is available. Some results showed that the feedback of channel information from the receiver to the transmitter improve the performance of orthogonal space-time block coding (OSTBC). With OSTBC, the unquantized, but not perfect, channel information was used to effectively combine the transmit beam-forming. In some results, it is shown that the diagonally weighting scheme using the quantized feedback achieves the good performance and the robustness to the feedback channel errors.
However, in relation to STTCs, there is no disclosure about a design of diagonal weighting scheme that uses quantized feedback.